ISM unable to apply policy to index as "admin"

Open-Distro: 1.9.0
In the ISM I have created a new policy.
However when I try to apply that policy to an index I get
[security_exception] no permissions for [] and User [name=admin, backend_roles=[admin], requestedTenant=null]

This confuses me as I am using the internal “admin” user; shouldn’t this have permission to do anything?

I have seen a few questions about this here or there on google but never a detailed explanation or actual resolution!
Any help would be appreciated.

@dbbaughe Can you shed some light on this?

I realised after I posted that I had included the .opendistro_security index when trying to apply the policy.
The policy was snapshot so I assumed that we would want to include the system indices in any snapshot.
However as it worked when I excluded .opendistro_security; I am guessing that this index should not be included in a snapshot, or any ISM policy, and that its the error message thats at fault; that this is not an auth issue per se, but that .opendistro_security should never have a policy attached!
Is that a reasonable conclusion ???

@boatmisser you are correct, as security index contains sensitive information, therefore in order to snapshot and restore the security index - admin certificate would need to be used. more details can be found here: Take and Restore Snapshots - Open Distro Documentation. Hope this helps